/Engine/Source/Runtime/CoreUObject/Public/Misc/PackagePath.h
Report the extension this PackagePath uses for the given segment
the EPackageExtension for the given segment, which is possibly EPackageExtension::Unspecified or EPackageExtension::Custom for EPackageSegment::Header
EPackageExtension GetExtension ( EPackageSegment PackageSegment, FStringView & OutCustomExtension ) const